Simultaneous removal of Cd(II) and As(III) from co-contaminated aqueous solution by alpha-FeOOH modified biochar

A novel alpha -FeOOH modified wheat straw biochar (alpha -FeOOH@BC) was developed and the findings of the current study showed that alpha -FeOOH@BC is an efficient material for the simultaneous removal of cations (Cd(II)) and anions (As(III)) from aqueous solutions. The SEM, FTIR, and XRD analysis proved that alpha -FeOOH@BC was covered by alpha -FeOOH. In the single adsorption system, the maximum adsorption capacities of alpha -FeOOH@BC for Cd(II) and As(III) were 62.9 and 78.3 mg/g, respectively. In the dual adsorption system, the maximum adsorption capacities of alpha -FeOOH@BC for Cd(II) and As(III) dropped to 39.3 and 67.2 mg/g, respectively. The adsorption capacities of Cd(II) and As(III) by alpha -FeOOH@BC were much higher by BC and alpha -FeOOH both in single and dual adsorbate system. The adsorption results were well fitted by the Langmuir and pseudo-second-order kinetics models. The Cd(II) and As(III) co-adsorption on alpha -FeOOH@BC had a competitive effect, and the dominant adsorption mechanisms were co-precipitation and ion exchange. Our study showed that alpha -FeOOH@BC could be an effective remediation material for Cd(II) and As(III) co-adsorption from aqueous environment.